Eight pieces of advice for those thinking of buying an iPhone 6 or 6 Plus

The launch day is over, the phones are now on shelves, and you can expect massive sales of the iPhone 6 and 6 Plus over this weekend. Not since 2010 have there been such long lines for, or insanity about, a new "i" device. I expected nutsville, even with a pre-order option, but nothing like this.

To be honest, the frenzy defies logic and there must be some kind of mob mentality driving it. I am reminded of Windows 95's launch nearly 20 years ago. Some people will point to past iPhone launches as being as big or bigger. No. iPhone 4 was the last gigantic debut weekend, before Apple started taking pre-orders, a mechanism that shifted sales away from the big day. iPhone 6 and 6 Plus are much larger when factoring in those 4 million first 24-hour pre-orders (and others) ahead of 19 September store openings.

Anyhow, if you're prowling about for either of Apple's newest handsets, I present eight things you should know about (in no order of importance):

1. iPhone 6 Plus is even bigger than you think. Unless already using a phablet, you will find the Plus-size device to be just that. It is ginormous. I stood alongside a woman in a Verizon store yesterday as she compared her iPhone 4S to to the 6 Plus and gasped: "It's so big!"

Strangely, the store only displayed the larger handset, which was sold out. She almost bought the 5S, until another customer pulled out the 6. "Oh, that's good", she said.

2. Good luck finding iPhone 6 Plus. The thing is sold out pretty much everywhere. I randomly called Apple Stores first thing on Saturday, and none had the thing. You can wait or go smaller, which is my recommendation for the majority of buyers. By the way, shortages feed the Apple marketing machine - and I question how often they're deliberate. Short Plus supplies ensure lots of blog posts, news stories, and social shares, which are worth millions in free marketing.

3. It's a design feature, not a flaw. For reasons that make no sense to me, the new iPhones have roundish rather than flat sides. In my handling of the iPhone 6, I found it's a slippery sucker as a result. No phone has ever made me worry about drops. I bought my first cell phone in 1997 and have never busted one, but holding Apple's handset makes me as jittery as watching the latest "Paranormal Activity" instalment. If you need a case to use a super slim smartphone isn't there something you should question about the design?

4. So, yeah, you really want to slap a case on the back. Apple's cases - five in leather and six in silicon - are excellent choices and really are the only ones in stores today. They feel great and provide the grip that should be on the device but isn't. What an upsell gimmick, eh? So add at least $35 (£20) to your purchase price.

5. Do spend the extra money on AppleCare+. The plan extends the warranty to two years and gives you up to two breakage/damage replacements for $79 (£50) each. Given that these phones are larger than what existing iPhone users are accustomed to, the slickness of the aluminium back, and questionable roundish sides, drop risk should concern everyone.

Related: First person in the world to buy iPhone 6 drops it on live TV

6. Don't buy either of the 16GB models. You will regret the decision later on. Spend the extra £80 for 64GB. It's what Apple wants you to do anyway, otherwise 32GB would be the smallest option (damn, retail tactics). The 16 gigger lets the company keep the entry price down but, by comparison, makes the four-times capacity model a better value proposition - as long as you don't mind spending more. To emphasise: You will want the extra storage. Just ask anyone trying to scrape off 6GB of free space on older iPhones to install iOS 8.

7. Expect problems setting up with Apple ID and restoring apps. As I often say, sync is the killer app for the cloud-connected device era. But in observing two different iPhone 6 models, iCloud sync either needs work or labours under the load of way too many people setting up new devices all at once (hopefully the latter scenario). My restore from backup is so slow that a day after receiving the phone, it's not done. So I tried manually installing from the App Store. Geez. Should Beats or Pages take 12 hours to download? As I write, they're not installed yet.

8. And finally, iPhone 6 is better than you think. The iSheep - as the Android Army and other fanboys call them - can only grow in numbers now. Because iPhone 6 is arguably superb (except for the little dropsy thing). The device feels great, looks better than in the photos, and performs outstandingly in all the ways that matter most. I strongly recommend the 64GB model for most buyers, many of whom will be Android Army deserters.

Read more: iPhone 6 vs iPhone 6 Plus: Which is better value?